Simi Valley was a sleepy Southern California suburb in 1979, one frequently ranked near the top of surveys of America’s safest cities — in large part because hundreds of police officers from nearby Los Angeles lived there.

This undated photo provided by the California Department of Corrections and Rehabilitation shows Craig Richard Coley. Gov. Jerry Brown on Wednesday, Nov. 22, 2017, pardoned Coley, a man convicted of killing his ex-girlfriend and her 4-year-old son nearly four decades ago after modern DNA tests suggested he was probably innocent. Coley, 70, has consistently maintained his innocence since he was arrested the same day 24-year-old Rhonda Wicht and her 4-year-old son, Donald Wicht, were found dead in her Simi Valley apartment on Nov. 11, 1978. (California Department of Corrections and Rehabilitation via AP)

The city, however, was shaken when residents awoke on Nov. 11, 1978, to learn of the slaying of a 24-year-old woman and her 4-year-old son. Rhonda Wicht had been strangled and her son, Donald, smothered in his bed.

Wicht’s former boyfriend, Craig Richard Coley, was arrested on the same day police found the bodies and eventually convicted.

For the next 39 years he steadfastly maintained that he had never killed anyone. Earlier this week, the police chief and district attorney indicated they believed him. On Wednesday he was pardoned by Gov. Jerry Brown.

Coley, now 70, walked out of a High Desert prison just hours before Thanksgiving, becoming the latest of numerous prisoners to be freed after advanced forensic technology that analyzes DNA showed they either didn’t commit the crime or someone else did.

Neither Coley nor a representative for him could be immediately located.

In an application for clemency that Coley himself filed from prison four years ago, he said a former police detective had framed him by destroying crucial evidence.

“The crimes were not committed by me and had the detective not destroyed the exonerating evidence (including semen and hair), the real suspect(s) could have been apprehended,” Coley said. He named a retired Simi Valley police detective he said could corroborate his story.

On Monday, Simi Valley Police Chief David Livingstone and Ventura County District Attorney Gregory Totten told reporters they had begun reviewing Coley’s case last year after a retired detective expressed concerns about the conviction.

“As district attorney, I must tell you I look forward to the day when I can shake Mr. Coley’s hand, apologize to him for the injustice he suffered,” Totten said.

The trial judge had ordered evidence destroyed after Coley exhausted his appeals, but investigators retrieved records from Coley’s relatives and located biological samples at a private lab.

Using advanced techniques not available at the time of his trial, technicians didn’t find Coley’s DNA on a key piece of evidence used to convict him. Instead they found DNA from other people, whom authorities have not publicly named. The evidence was not identified.

“I am also hopeful,” Totten said, “that one day soon we will bring to justice the violent man responsible for this most horrific crime.”

Coley’s arrest was a media sensation in Simi Valley in 1978, when the population of 75,000 was half what it is now. Some public officials complained at the time that newspapers seemed to be attempting to exonerate him in stories that suggested someone else might be involved.

The 24-year-old restaurant manager and son of a retired police officer had never been in trouble. But authorities maintained Coley was angry and despondent after learning Wicht was breaking up with him.

She was strangled, apparently with a macrame rope, and her son was suffocated. Their bodies were found in their apartment.

Coley’s first trial resulted in a hung jury, with jurors split 10-2 in favor of conviction. He was tried again in 1980, found guilty and sentenced to life without parole.

During his decades in prison Coley was cited as a model inmate, avoiding gangs and violence and embracing religion.

“The grace with which Mr. Coley has endured this lengthy and unjust incarceration is extraordinary,” Brown wrote in his pardon.

The governor said he asked the state parole board more than two years ago to look into Coley’s conviction. He said former law-enforcement officials believed Coley was either wrongfully convicted or framed.

“This case is tragic,” Livingstone and Totten said in a news release. “An innocent woman and small child were murdered. Craig Coley has spent 39 years in custody for a crime he likely did not commit.”

Associated Press Writer John Rogers in Los Angeles contributed to this report.